Spring/Summer project…

Using two 8″ subs with a Pyle 1200w amp. (JCWhitney special)



6/6/10 – Got the seat removed tonight and discovered that the frame is a bit different than that shown in the forum where I got the idea from. Not too much, but enough that the box requires a redesign. Completely. The idea remains the same, but the box may actually be a little simpler than the example.

6/9/10 – Started construction. Went fairly well. Got most of the parts cut. Had to custom cut a few pieces. Will take measurements and update the CAD layout dimensions before posting the plans.

6/12/10 – Finished! Installed and working. Sounds GREAT! I estimate approximately 8-10 hours of labor total. Haven’t updated or posted plans yet.

Materials
(1) 3/4″ MDF 4”x8′ sheet. (1/2 sheet will suffice if you can find it pre-cut)
(1) box 1 5/8″ drywall/wood screws
(1) 3/4″ metal angle (36″ is more than enough)
(1) tube Liquid Nails Adhesive (wood glue will work, but Liquid Nails will be better for holding and sealing)

Tools
Metal grinder/cutter
Table Saw
Sabre Saw (Band saw would also be handy)
Drill (w/philips driver and counter-sink bit)
Caulk gun (for tube of Liquid Nails)
Pencil
Utility knife or electric knife – or both
Soldering iron (recommended)
Wood Clamps or C-Clamps

This link is to a forum that shows a 10″ sub installed in a rear seat. This is where my plans originate from. Again, while the idea remains the same, the design and dimensions have changed: www.jeepz.com

Another link shows plans and dimensions for a box made for a 97-02: www.sirgcal.com

Plans with dimensions. Some dimensions will need to be tweaked in construction.

Here are pics of my project. Click on a photo below to enlarge.

Jeep-Subwoofer
Original (temporary) setup
Original (temporary) setup
Original (temporary) setup
Original (temporary) setup
Original (temporary) setup
Original (temporary) setup
Bottom after seat-cover removed. Upholstery easily zips off.
Bottom after seat-cover removed. Upholstery easily zips off.
Remove cross bars.  I used an electric cutting tool (grinder) for ease.
Remove cross bars. I used an electric cutting tool (grinder) for ease.
Cross bars removed.  I painted over the bare metal with satin black to prevent rusting.
Cross bars removed. I painted over the bare metal with satin black to prevent rusting.
Again with cross bars removed.
Again with cross bars removed.
Pieces cut per plans. Assembly begins. Several pieces were measured and cut as I went along for tight fit.
Pieces cut per plans. Assembly begins. Several pieces were measured and cut as I went along for tight fit.
Pieces cut per plans. Assembly begins. Several pieces were measured and cut as I went along for tight fit.
Pieces cut per plans. Assembly begins. Several pieces were measured and cut as I went along for tight fit.
Pieces cut per plans. Assembly begins. Several pieces were measured and cut as I went along for tight fit.
Pieces cut per plans. Assembly begins. Several pieces were measured and cut as I went along for tight fit.
Liquid Nails was used.  Regular wood glue would have probably sufficed.
Liquid Nails was used. Regular wood glue would have probably sufficed.
Since I bought the Liquid Nails, I went ahead and used it instead of the wood glue.  Plenty of wood screws held it all together.
Since I bought the Liquid Nails, I went ahead and used it instead of the wood glue. Plenty of wood screws held it all together.
Screws went in pre-drilled, countersunk holes.
Screws went in pre-drilled, countersunk holes.
Some pieces were cut on a band saw.  It made several small cuts quick and easy.
Some pieces were cut on a band saw. It made several small cuts quick and easy.
One of the "measure and cut as you go" pieces.  Piece is included in plans, but much better to actually measure it as you go for a better fit.
One of the "measure and cut as you go" pieces. Piece is included in plans, but much better to actually measure it as you go for a better fit.
Getting close to all together.
Getting close to all together.
Some MDF split when I screwed it together, even after I pre-drilled it.  I used wood glue and clamped the split pieces together until dry.
Some MDF split when I screwed it together, even after I pre-drilled it. I used wood glue and clamped the split pieces together until dry.
Inside view of the corners.
Inside view of the corners.
Clamps were used to hold pieces tightly together during assembly.
Clamps were used to hold pieces tightly together during assembly.
Inside view of center braces.
Inside view of center braces.
Front corner view.
Front corner view.
Inside front corner view.
Inside front corner view.
One of many test fits.
One of many test fits.
You can never have enough test fits.
You can never have enough test fits.
I added a groove, or a cut-out for a better fit.
I added a groove, or a cut-out for a better fit.
This groove is where the hinge bracket attaches on the frame. Not necessary, but just for a better fit.
This groove is where the hinge bracket attaches on the frame. Not necessary, but just for a better fit.
Cut some 3/4" angle to length and drill some holes.
Cut some 3/4" angle to length and drill some holes.
Angle bracket attached to front of box with screws.
Angle bracket attached to front of box with screws.
Angle bracket in back
Angle bracket in back
Attach to seat frame with short self-tapping sheet metal screws.
Attach to seat frame with short self-tapping sheet metal screws.
Marking the cut-out for the speakers.  Bottom is still only temporarily attached with screws at this point...  Just in case you cut something incorrectly...
Marking the cut-out for the speakers. Bottom is still only temporarily attached with screws at this point… Just in case you cut something incorrectly…
Cutting with jig saw is the best solution.
Cutting with jig saw is the best solution.
Start with drilling a pilot hole.
Start with drilling a pilot hole.
One down, one to go...  I also drilled a small hole to run the wires thru toward the bottom center.
One down, one to go… I also drilled a small hole to run the wires thru toward the bottom center.
Another test fit.
Another test fit.
Another test fit.  All's good so far.
Another test fit. All's good so far.
Another test fit.  Also check the sound.  All's good so far.
Another test fit. Also check the sound. All's good so far.
Time to glue and screw the bottom plate to the box.
Time to glue and screw the bottom plate to the box.
Now to cut the seat foam.  Mark the cut lines with a sharpie before starting.
Now to cut the seat foam. Mark the cut lines with a sharpie before starting.
An electric knife is great for removing foam.
An electric knife is great for removing foam.
You can always take more off, but it's difficult to add it back.  Take a little at a time to be safe.
You can always take more off, but it's difficult to add it back. Take a little at a time to be safe.
Test fit.  Fits good.  Time to put the seat cover back on.
Test fit. Fits good. Time to put the seat cover back on.
Test fit.  Fits good.  Time to put the seat cover back on.
Test fit. Fits good. Time to put the seat cover back on.
Seat cover back on securely.  All fits well.  Have to round of a corner of the box as to not put too much stress on the vinyl and maybe rip it someday.  Just grind it down a bit.
Seat cover back on securely. All fits well. Have to round of a corner of the box as to not put too much stress on the vinyl and maybe rip it someday. Just grind it down a bit.
I left a little extra foam on the seat to make it a little more cushioned so it looks a little puffy...
I left a little extra foam on the seat to make it a little more cushioned so it looks a little puffy…
Ready to test fit again...
Ready to test fit again…
I like it...
I like it…
Time to cut holes out of carpet on bottom of seat.  Just use a sharp utility knife and follow the circle.
Time to cut holes out of carpet on bottom of seat. Just use a sharp utility knife and follow the circle.
Wire up the speakers and install.  I soldered them for a good connection.
Wire up the speakers and install. I soldered them for a good connection.
Installed.  Add the speaker covers next and add the custom plug on the speaker wires.  (4-pin molex connector)
Installed. Add the speaker covers next and add the custom plug on the speaker wires. (4-pin molex connector)
Wires relocated on amp.  I glued two 1/4" MDF pieces on the bottom of the carpet to screw the amp down.  You can see female side of the molex plug here.
Wires relocated on amp. I glued two 1/4" MDF pieces on the bottom of the carpet to screw the amp down. You can see female side of the molex plug here.
Relocated the RCA input wires also.
Relocated the RCA input wires also.
Seat back and bottom re-assembled.  Ready to final install.
Seat back and bottom re-assembled. Ready to final install.
Installed!
Installed!
Connected and tested... IT WORKS!!!
Connected and tested… IT WORKS!!!
Even with the extra cushioning it still folds up behind my custom made center console.
Even with the extra cushioning it still folds up behind my custom made center console.
Seat back in regular position.
Seat back in regular position.
Stock look.  Custom sound!!  Storage room back!
Stock look. Custom sound!! Storage room back!
Before   ---    After
Before — After


12 Comments

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  1. avatar Carl said:

    July 13, 2010 @ 11:10 pm

    I’m planning on attempting this. But what would you think if instead of putting them under the seat Put them on the back of the seat. I haven’t gone and looked at my seat so i have no clue. But if it would work, putting them on the back of the seat would allow more bass.

  2. avatar gnfoster said:

    July 14, 2010 @ 9:28 am

    Thanks Carl.

    I thought about the back of the seat also, but I didn’t check it out to see how the structure of it was. One of my reasons for this project was for space saving and another was to help hide the speakers, so I opted for the bottom.

    I also believe that you actually get more bass from the bottom firing speakers. Bass frequencies are non-directional. They also use the surrounding materials for frequency transmission. You’ll notice that by changing the placement of your home theater sub to different locations in the room you achieve a different sound (although it be moderate usually it can be a dramatic affect).

    So… I put them in the bottom to bottom fire… So they fire directly at the floorboard…so I can feel the thump… Also because I wasn’t comfortable tearing into the back of the seat… which doesn’t really make sense, because I tore into the bottom… hmmm…. Maybe I’ll try BOTH!… not a bad idea actually…..

    The 8″ subs are nice, but I’m sure low-profile 10″ are much better. The nice part of how I made the cabinet is that I can easily change out the bottom panel to fit another size speaker in the future if I wish. I did cut the carpet on the bottom of the seat, but I’ll deal with that placement issue if it arises.

    I would be VERY interested to see if could be efficiently done in the rear of the seat. If you attempt it, please take photos and let us know what you find!

  3. avatar Carl said:

    July 18, 2010 @ 11:40 pm

    I’m aware of the bass frequencies fact. Its just from personal experience i have noticed i get the most reward from a woofer if it faced backward in an vehicle such as an suv (not vehicles that have the sub in a sealed trunk…not sure there). so that’s why i thought up the back instead of the bottom.

    Another thought is that sense you had to remove some foam cushion from the seat it wouldn’t be as much of a sacrifice to have less cushion on the back.

    Maybe if i get a good chunk of free time i dig through the seat a while and take some measurements, and compare the two.

    Who knows I could put two on the bottom and two on the back lol. that would be PLENTY of bass for a Jeep. (But where to put the amps :D)

  4. avatar gnfoster said:

    July 19, 2010 @ 12:28 am

    See…. NOW your thinking. Two in the bottom and two in the back! The amps will fit snugly under the seat! Of course with that much bass in the Jeep, no one will want to ride in the rear seat anyway, so you can just sit them in the rear seat!

    I was looking at the seat back tonight. I didn’t tear into it or anything, but was thinking about your comments. I agree with the sacrifice of seat foam. Better to lose it in the seat back than the seat bottom. You do however have much less real estate to work with in the seat back. It’s not near as thick as the bottom. Plus it’s not as hidden. (if that’s even a concern)

    One of my previous thoughts was to use the seat back for installation of front firing 6x9s. Definitely would mess with the comfort of back seat riders though.

    Another idea was to build a sub into the spare tire carrier somehow. Yeah… that seems sorta lame now that I see in in type….

    I’m still trying to figure out an economical way to deal with the lousy front speaker placement. Maybe some bass blockers on those 5.25″s will help a bit…

    My wife just came back in town after working at camp for six weeks. It was the first time she got to hear the installed subs. She loved the sound! Very happy… SCORE!!!

    Very interested in your findings about the seat back vs. seat bottom.

  5. avatar Carl said:

    July 19, 2010 @ 10:02 pm

    Really quick comment. (Busy)

    I was thinking maybe powerful yet shallow 10” (or 2 10”s) sub might fit in the back.

    And for the bottom maybe 2 12”s if there is enough airspace in the sub box.

    I was thinking the 10’s for the back because usually you can find a shallower sub the smaller cone size gets for the price(to a point). Also personally i think its good to have a 10” and a 12” they both have there own range for certain lows and low lows :D. (Every subs got a sweet spot :p)

    I’m going to be working all week and weekend so maybe I might do some late night work.

  6. avatar Steve said:

    January 26, 2011 @ 12:46 pm

    Since you have had this mod for a while now I have a question regarding comfort of the back seat.

    I have 3 children (10, 13, and 15) and my back set is ALWAYS being used! They are kids so they don’t need the comfort that my 40-year-old butt demands but at the same time I don’t want them to all of a sudden hate riding in the Jeep because the back seat is too damn harsh/hard.

    If it’s unnecessary I don’t want to add any work to this project but I’ve thought about modifying the brackets (I’m a welder so this would be a fairly easy mod) to raise the seat 1-1.5″ which would allow me to keep 1-1.5″ additional foam in the seat.

    Comfort is important – Comments/input please

  7. avatar gnfoster said:

    January 26, 2011 @ 2:11 pm

    Well, I did sacrifice a bit of comfort. 99% of the time we are riding our Black Lab around in the back seat. He doesn’t complain. He doesn’t complain when he has to eat dog food either, but…

    I have ridden on it a couple times and it is less comfortable than it was. I left approximately 1 to 1 1/2″ of foam, but the bottom seat top actually sets about 1″ higher than stock. It’s hard to tell in the photos, but it does. The foam is quite dense. The comfort came not only from thicker foam, but also from the thin bracing on the seat-bottom.

    It’s not too bad, but it is nothing like it was. When I sit in the seat, I actually sit higher because it doesn’t have as much give as originally. It can get rough when you’re on a bumpy road. It would likely be very uncomfortable when off-roading.

    I made this box as deep as possible for sound and still have the seat-bottom carpet cover the box. It’s a very tight fit. Sure makes for a heavy seat to take in and out also…

    Raising your seat may allow you to leave extra foam, BUT without making the box thinner it may not fit into the seat cover. To keep it as original as possible I made it fit into the seat cover, therefore, it could still only be so deep. Even it I took ALL of the foam, it could still be only so deep. Raising the seat would not help me because of those limitations still. If I didn’t care if the seat-bottom carpet was left on, I could have dropped the box down a bit and left more foam.

    You definitely need more foam than I left if you want comfort. The kids may even be willing to sacrifice comfort for the sound, but don’t take them off-roading with this mod.

    Would love to see pics if you give it a shot!

  8. avatar gnfoster said:

    July 11, 2011 @ 1:32 pm

    Just realized what I did here… When I added the center support for the box, I did not create a divider, only added support braces. Since this is a sealed system, should I have created a divider to separate the two sub cavities instead of just braces?

    What’s your opinion?

  9. avatar ryan said:

    December 8, 2011 @ 12:11 pm

    i would like to do this to my 98 sahara. do you have plans drawn up that i could print out?

  10. avatar gnfoster said:

    December 8, 2011 @ 2:15 pm

    I do. I will try to get them posted here ASAP.

  11. avatar Matt said:

    October 21, 2012 @ 6:36 pm

    as far as placing the amp im a sound guy so i literally need my entire trunk space so having the amp on the ground as little as it is just didnt work for my plans so i decided that ill put it under the driver seat and run all the wiring to there also i dont remember if you did this or not but i plan on getting a connector set up so i dont have to disconnect the speaker wire from the amp in order to remove the seat just simply unplug the seat as foolish as that sounds! im excited to do this and itll cost me under $200 to do. which saves me alot of money and trunk space also i wired my stereo to run both my built in center console sub while running the built in! so even if i remove my seats i still have a decent amount of bass in my car

  12. avatar Matt said:

    October 28, 2012 @ 3:15 pm

    Well I finished my own design for the sub box I made it simple! Took 3 hours to build I just need the subs and im done! Also I put the amp under the driver side seat so when I take out my seat I have the whole trunk space. I can’t wait to hear it! my seats are about as comfortable as a mustangs so im not complaining lol.

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